Nuclear rocket flow control



1965 w. A. LEDWITH ETAL 3,168,807

NUCLEAR ROCKET FLOW CONTROL.

Filed Aug. 8. 1961 4 Sheets-Sheet 1 PROGRAMMER F'IGJ BIMJ;W

1965 w. A. LEDWITH ETAL 3,168,807

NUCLEAR ROCKET mow CONTROL Filed Aug. 8. 1961 4 Sheets-Sheet 3 65 Fl (3 -3 --CH/7M5P P/PESSUAE 7 61052- WZV' Md HTTT I I 4 g F'ICB-4 1965 w. A. LEDWITH ETAL 3,

NUCLEAR ROCKET FLOW CONTROL 4 sheets-sheet 4 Filed Aug. 8' 1961 P0615621 AZ fi/ N acts as a neutron moderator.

pump to cooling jacket 16.

leading to the turbine.

copending application Serial No. 112,830, filed ll lay 26,

This part of the hydrogen then flows through shut oil valve 15 in conduit 14 and to cooling jacket 16 which surrounds both convergent chamber 17 and divergent chamber 18 in rocket thrust chamber 19 in heat exchange relationship. The hydrogen in cooling jacket 16 is heated by the heat absorbed from the hot gases in chambers 17 and 18, thereby cooling the Walls of chambers 17 and 18. The hydrogen then flows through annular chamber 29 and around reactor control drums 21 located therein to serve the further purpose of cooling the control drums.

Reference will now be made to the remaining part of the hydrogen discharged from the first stage of pump 11, i.e., the part not flowing through conduit 13. This part of the hydrogen passes through shut oifvalve 22 in conduit-12, and then flows through and cools shield 23 which is a tank .in which the high density hydrogen gen then passes through opening 24 and then through gamma shield 25-110 cool gamma shield 25 which is made up of sheets of depleted uranium having flow passa es therethrough for the flow of hydrogen. The details of the shield structure are shown in eopending application Serial No. 111,129, filed May-1 16; 1959, which'is assigned to the assignee of thepresent invention and to which reference is hereby made for the details of the shield construction. This part of'the hydrogen then'ilows from gamma shield 25 through conduit 26 to chamber 20 where it joins with and mixes with that part of the hydrogen which flowed from the second stage of the This mixture of thetwo This part of the hydro-.

parts of the hydrogen then flows from chamber 0' 4 chamber 27 and thence through the core of reactor 28 where it is further heated and then discharged through chambers 17' and 18 to be expanded to provide thrust.

I A part of the m'ntture in chamber 27 is bled therefrom to conduitfZSl to be used in a manner to be described below. I g r A part of the heated hydrogen in chamber 17 is bled therefrom to conduit 39. This material blcd from chamer 17 'to conduit 30" is at an extremely high temperature, and it is joined by and mixed with tehydrogen in conduit 29 to produce a mixture at a lower temperature which can be used as a power fluid for a, turbine without damage to the turbine elements or the ducting Reference is hereby made to 1961', now Patent No. 3,134,224, WhlCh iS assigned to the assignee of the present invention, for the details ofthe structure used in bleeding material from chamber,

17 and producing a mixtureat a usable temperature.

The mixture formed from combining the material bled' from chamber l7'withthe mixturebled from chamber 27 is delivered by conduit 31 to turbine 32 which is drivinglyconnected to pump 11 by'shaft 33.. Throttle valve 34 in the discharge passage 39 of turbine 32 controls the fiowthrough turbine 32 in a manner to be described below, and the power fluid-is expanded through turbine 32 .to drive pump 11. The power fiuid is then delivered by conduit 35 to auxiliary nozzles 35 and is expanded therethrough for added thrust or for vectorving purposes. i

31 rises above the desired level, valve 38 will be positioned to deliver a greater amount of the mixture in conduit 29 to form the mixture within conduit 31, and if the mixture in conduit 31 falls below the desired temperature valve 38 will be moved to deliver a lesser amount of the mixture in conduit 29 to form the mixture in conduit 3-1.

Programmer 56 functions throughout the period of operation of the engine to deliver signals of programmed operation preformance levels to turbine throttle valve 3-41, comparator 62, and drum control and actuator unit '64 via wires 56a, 55b, and 56C, respectively. These programmed signals establish the desired operational levels of the engine control components throughout the range of engine operation for start-up, steady state performance and shut down procedures.

The programmed signal to turbine throttle valve 34 controls the area of turbine discharge passage 39, thereby regulating the output of turbine 32 and hence controlling hydrogen fiow from pump 11 to thrust chamber 19. The pressure in chamber 17 is art indication of ac- .tual hydrogen flow, and this pressure is transmitted by pressure sensor 66 and line 68 to turbine throttle valve 3-? to modify and adjustthe area of discharge passage 39 to maintain the desired propellant flow.

- programmed signal to drum control and actuator depositions control drums 21 and establishes the desired power level of the reactor. The programmed signal to comparator 62 is an indication of the temperature level in chamber 17' which should accompany a programmed-level of reactor power. The temperature level in chamber I17 'is's'ensed by a thermocouple type I .23. and modify the power level of reactor 28 to maintain the desired temperature level.

A further control feature is provided in an ion chamber systemconsisting of ion chamber 80 and amplifier 32 which is' calibrated to sense a high rate of change of reactor power level, hence sensing sudden large excursions inreactor power level; The signal generated by this'ion chamber system actuates solenoid valve 84 to deliver a supply of pressurized helium from storage bot-file 86 to drum control and actuator 64 via line 90 to override the drum control and drive control drums 21 to the shut down position.

Programmer shown. A-plurality of bus bars 92a and 921; are arranged in arcuate form. Each pair of bus bars 92a and 92b is connectedto a battery $4, the voltages of the several bat teries 94being'of diiferent levels. In the bank of bus bars shown, each battery 94 is connected to drum control and A fluid-filled temperature bu1b'37jis located inconduit 31- and senses the Itemperatureof; the mixture, in

conduit '31. Bulb 37'communicates with valve '38 in conduit-.29 and regdlatesthe amount of the mixture in' conduit 29 which is delivered to be mixed with-the ma- ;lterial bled from chamber l7. In this mannerthe con- .stituents of the mixture in conduit 31 is altered and the temperature'of'the mixture in conduit Ell-is maintained at a substantially constant value which is pn'eferably as highas is suitable for powering turbine 32 Without thermal damage to the turbine. :The temperature of the mixture inconduit 29 is substantially below the temperature in chamber 17. Hence, if the mixture in conduit actuator 64. A clockwork mechanism 96 drives an insulated shaft 98 on which is mounted a wiper arm 160 having an insulated portion'102 and aconducting portion 164., Closing of switch ltlticonnects battery 108 to clock a [mechanism 96 to rotate shaft'98 and move wiper arm 100 across the successive pairs of bus bars 92a and 92b. Conducting portion 194 closes the circuit between the pair of.

busbars with which it is in contact to deliver'a voltage 4 1 signal to drum control and actuator 64. It should be apparent that as conducting portion 104-contacts successive pairs of bus bars, the voltage supply to drum control and actuator 64 will vary. Programmer 56 consists of a group of bus bar banks such as described immediately above, s'eparate l banks communicating with. fthe turbine throttle valve 34,drum control and actuator 64 and comparator 62. Thus it should be apparent that programmed signals can be delivered to turbine throttle valve 34, drum control and actuator 64, comparator 62 and any other control sleeve 302 cooperate with housing 310 to form an annular chamber 312 to which conduit90 leads. Another annular sleeve 313 depends from gear 216 and is capable of rotation relative to sleeve 304, and a coil spring 314 extends between and is connected to both sleeves 313 and 304. i

Spring 316 normally holds sleeve 302 .in splined engagement with gear 216, and hence movement of gear 216 is normally transmitted through spline 3 00, spring 302,

sleeve 306 and sleeve 304 to drive control drum 21. If

. reactor 28 should experience a serious, sudden'excursion above the programmed power level, the ion chamber "system consisting-of ion chamber 80 and amplifier 82 will sense this high rate of change of power level and win-aen er a signal to open valve 84. .The opening of valve 84 will deliver a supplyof pressurized helium via" conduit 90 to' chamber 312 which will move piston 308 against spring 316 thereby disengaging spline 300 and disconnecting sleeve 3 02 from gear 216. Since gear 216 and worm 214 are of the-irreversible type, gear 216 and sleeve'3' 13 will beheld fixed, and spring '314-will drive sleeve 304 and hence controldrum 21to the full poison orreactor' shutdown position; Thus, the high" rate of change'cffpowerlevel sensed by'this' i'on chamber sysby programmer 56 and operates in emergency situations to drivej'control "drums 21 to-the reactor-fshut down 1 position; It will be understoodfthat there. are anum ber of'drum control andac'tu'ator units 64in thelsysteni, "one for each control drum 2.1 .1;

with the signaidelive'red via wires" 56c toJdrum control wand actuator 64.1: The signaldelivered to comparator 62 is a: measure of the temperature" which shouldfixist U Comparator 62 consists of a voltage divider made up of' resistor 250 and'a wiper arm 252 pivoted at'254, an ,electromagnetg256, -and"an.amplifier 25 8 which receives. signals from temperature sensor 70 via wires72iand energi'ze electromagnet 256. Amplifier 258' is calibrated to fmove wiper arm 252 in a clockwise direction ffor "tem- I peratures sensed by -.thermocouple 70 above a selected I reference 1BIIIPI3IHIQQ in a counterclockwise;direction for' temperatures below this;referenceftemprature. The a deviation of wiper arm252jrom' null positiomas shown,

' either in a' clockwise or counterclockwise,- direction, will dependgon thedegree to which the temperature sensed fby thermocouple 70 differs from the arbitrarily selected teni actuate sja scram mechanisrn which overrides the programmedpower-level for ther'eacto'r as determined 0 Referring to FIG. 5', fa signal is delivered totempera 17 'ture comparator 62 vialwires 56b,contemporaneouslyj H in chamber 17asa'result of the power level ofjreactor 28 called for by the signal deliveredfrom prp'grainmer 56 to drum control and actuator 64. f

The voltage signal" delivered from programmer 56. to;

i resistor 250 via wires 56b will be a constant at any one time and is represented in- FIG. Sby a battery of E volts. The voltage E'is a signal of the desired temperature withinchamber ,24, and resistor 250 is calibrated so that a voltageXds picked 0E resistor 250 when that desired fltemperature is reached A battery 266Lof Xjvolts-is placedin oneof the .wires' 73 to generate a current'opposedto'. the current generated in wires .73 by the volt-,

'age divideiz' ThusQwhen the desired temperature exists 1 in chamber 17, no current will pass through wires and hence no signaliwill be delivered to torque motor 160.

3 If the temperature in chamber 17 deviates from the programmed level, wiper 252 will be moved to vary the voltage picked off by wiper 252 and hence a current will pass through Wires 73 to torque motor to actuate drum control 64. An increase in the temperature in chamber 17 results in movement of wiper 252 in a clockwise direction about pivot 254 to increase the voltage picked otf by wiper 252 to produce a current in wires 73 from the positive terminal of battery 266 to the negative terminal thereof internally of the battery. Conversely, if the temperature in. chamber 17 drops below the desired level, then wiper 252 will be rotated in a counterclockwise direction to decrease the voltage picked 'ott' by wiper 252 and hence generate current in wires 73 from the positive to the negative plates of battery 266 externally of the battery. I

When programmer 56 calls for a different temperature within chamber 17, a'ditferent voltage E 'will be delivered via wires 56b to resistor 250. In the present embodiment, E will be increased over E when a higher temperatureis described in chamber 17. As this higher tem-. perature is approached within chamber 17,- wiper 252 will 7 be moved around pivot 254 in a clockwise direction toward the positive terminal of resistor 250, and hence it shouldbe apparent that resistor 250 can be calibrated so that the voltage X is picked off whenever thetemp'erature in chamber 17 is at the desired level. Conversely, when the voltage E is less than E, this being-the situation, when a lower temperature is programmed for chamber 17, Wiper 252 will be rotated in a counterclockwise direction about pivot 254 and the signal. will be delivered to drum control 64 via wires 73 'until the voltage picked 011 by wiper252 'is equal to the voltage X of battery 266. V a 1 a Operationf Prior to starting the rocket engine; control drums 21 fwill be in the full poison position and reactor- .28 will be shut-down. Valve 410-will be closedvto prevent the sow of hydrogen supply pressure to turbinethrottle valve -34 and drum. control and actuator 64; valve-412will be closed to preventthe flow of'hydrogen actuating pressure to shut' otf valves 15 and 22; and hence valves 15 and 22 will be closed; valves 414 and 415'will'be closed to prevent the flow of hydrogen actuating pressure to cool down valve'416 and afterheat removal valve 417. Liquid hydrogen fromtank 10pwill surround two-stage pump 11 and will fillconduits 12 and 14'up to shut off valves 22 and 15, respectively. v

The operation of the rocket engine is initiated by closing switch 106 to actuate clockwork mechanism 96. The bus bars in programmer 56 are so arranged that solenoid valve 410 is first actuated to allow pressurized hydrogen from tank 400 to flow through conduits 402 and'404 to deliver supply pressure to. throttle valve '34viaconduit '406and' to drum control 64 via conduit 408;. -'Program-" mer 56 next' delivers ,a si'gn'al to drumlcontrol64 'via wires 560 to 'move controldrumsi21loward the reflect v ing position at a'preset rate.' A signal is then delivered from programmer 56'tojsolenoidvalve'414 to open valve 414 ,for a predetermined short period of time. When valve 414 is opened, pressurized hydrogen flows from con duit 404 through branch conduit 418 to openficooldown valve,- 416 to vflow hydrogengthrough pump 11 to cool it V r "and overboard through conduit 420.I After a pr'edet'en "mined time has elapsed,the signal will be removed from valve 414 and valve 416 will close to end the coolingflow;

A signal is then delivered from programmer 56 to open solenoid valve 412, and pressurized hydrogen then flows from conduit 404 to conduit 422 and branch conduits 424 and 426 to open shut valves 15"and 22. V

Upon' the opening of shut-off valves 15 and 22, the

6 hydrogen flowsthrough the core ofreactor 28 to chambers 17' and 18 in thrust nozzle 19 in themanner previousl-y described to be expanded to produce thrust. The V v components such as solenoid valves in any predetermined manner and timed relationship according to the position and length of the bus bars.

Turbine throttle valve The details of turbine throttle valve 34 and the control unit therefor are shown in FIGS. 7 and 3, respectively. The details of the turbine throttle valve and the control therefor form the subject matter of copending application Serial No. 106,096, filed April 27, 1961, now Patent No. 3,071,345, and copending application Serial No. 106,095, filed April 27, 1961, respectively, both of which are assigned to the assignee of the present invention, and reference is hereby made thereto for a more complete detailed description of the operation thereof.

Referring to FIG. 7, the discharge passage 39 of turbine v 32 is formed by a stationary annular outer wall itl anda moveable inner wail 41 which constitutes a throttle valve. The wall 41 is connected by struts 42 to a double-acting piston 43, the faces 44 and 45 of which are pressurized by the introduction'of pressurized 'liuidto chambers 46 and 47, respectively; Springs 48 urge piston 43 to the right and springs 49. urge. piston 43' to the left. When no actuating fluid is present in either chamber 46 or 47, piston 43 assumes the positionwherein the forces of springs 43 and 49 are equalized. This establishes an area for passage 39 corresponding to the nonactuated position of piston 43. f A signal from programmer '56 is.transmitted to torque motor 11%, FIG. 3, to positionflapper 112 which is pivoted at 114. Hydrogen under pressure is stored in tank 4%, FIG. 1, and is supplied by conduit 402, branchconduit 404 and conduit 406 to chamber 120, FIG. 3, and thence to conduit 122.. Conduit 122 has a fixed restriction 124 at one end thereof and avariable area oriflce'126 at the other end thereof, the size of variable area"orifice 126 3 being determined by a'position 'of flapper 112. The electricai signal which positions flapper 112'establishes a reference pressure in conduit 122 which. is indicative of the. desired pressure in chamber '17. The pressure in conduit 122 is delivered to the interior of bellows 128-to'position are free end130thereof and imposea force-on flapper 132 which is an indication of the desired pressure level in chamber-1'7. Pressure in conduit 122 is also delivered to Y the interior of beilows 134, the free end 1360f which is in contact with flapper 112 as a feedback device. The actual 1 pressure in chamber 17 is transmitted via conduit 68 to .theinterior of bellows 13 8 to move the. free end- 1 3 thereof and impose-a load on'flapper 132which is a measure of the actual pressure in chamber 17. Flapper 132 is pivoted at 142 and moves about pivot 142m vary theareas oforilices 14 4 and 146 in conduits 14S and 159,1'espectivel y. Conduits 148 and 15% have fixed restrictions 152 and 154 therein, respectively. If the pressure in chamber I 17 as sensed by bellows138 differs from the programmed chamber; pressure as sensed by bellows 123,.flapper 132 r, will be-pivoted. to vary the arcasof orifices 144 and 1'46 in propellant flow from the programmed level will be sensed by bellows 138 and will result in changes in the area of discharge passage 39 in. the manner described above. These area changes regulate and control the output of turbine 32 and hence the output of pump 11 and control and maintain propellant flow at the desired programmed level.

Drum control and actuator The details of drum control and actuator 64 are shown in FIGS. 4 and 6. These control components form the subject matter of copending applicationsSerial No. 111,- 124, filed May 8, 1961, now Patent No. 3,141,383, and Serial No; 113,990, filed May 29, 1961, both of which are assigned to the assignee of the present invention and to which reference is hereby made for a more detailed description.

Referring to FIG. 4, programmer 56 transmits an electrical signal of desired reactor power level to torque motor via wiresStiq. This signal causes flapper 162 to move about pivot 164m vary theareas of orifices 16 6 and 158 in conduits and 172, respectively. Conduits 170 and172 have fixed restrictions 174 and 176'therein,

and these'conduits are supplied with pressurized hydrogen from tank etlo'viaconduits 402 and 408,'see FIG., 1.

Branch conduits 180 and 182 downstream of the fixed restrictions lead to chambers 184 and18 which are formed by bellows ldh and 190. Disc-shaped end plates 194m attached to the'free ends of bellows 188 and 190,

respectively. Bellows 188 and disc 192"-are contained within chamber 196, and disc 192 serves to close off chamber. 196both from vent 198 and from branch conduit' 2% fupstream of;fiXed-r es'triction-174. Similarly, bellows .190 and plate 194are contained Withinchamber 9 2,02and disc, 194serves to close off chamber 262 from I conduit 204 upstream of-fixed restriction vent .1 98 i and QMo'vement of flapper in 'response toithe signal aslivered totor'que motor- 160 via wires Soc will cause an increase inpressure in. onejof'the chambers 184 .and 186 ,andia decrease in pressurein the other ofthe chambers.

' Assuming that chamber .186 experienced anincrease in and hence change, the pressures in conduitsf148 and.150.'

If the pressurein chamber 17 should'rise above the desiredlevel, thereby indicating an excesspropellant flow to chamber 17, flapper 132 will berotated in. a clockwise direction to increase the pressure of the actua'ting fluid in [conduit 148 and decrease the pressure of. the actuating Yfiuid in conduit 15s. This w illcause an increase in pics- "sure in, chamber do and a decrease iii-pressure in chamber 7 f 47, and piston 43,-and hence throttle valve 41, will be moved to 'the'leftto reduce the areaof discharge passage I i 39-. Reducing'the'area of passage 39 will reduce the'flow through turbine 32, thereby reducing the output of turbine 32, and. hence decrease thepressure in chamber 17'by, reducing the amount of hydrogen delivered from 'pump'11. Conversely, if the pressure in chamber 17 falls below the 1 pressure, disc 1-94. will be rotated about its contact with [vent conduit 198 to connect branch conduit 204 to cham her 202. to Ideliver high pressure helium to chamber 202. Simultaneously, a decrease in pressure'in chamber 184 will cause dise192torotateabout its contact .with conk duit 184 to. connect. chamberf196..to vent conduit 1593 thereby reducing thepressur'e in chamber196. The increased pressure in "chamber 202" and thedecreased pres-1 sure in chamber 196' will cause a flow throughconduits 203 and 205 through gear niotor2t16 to rotate gears 20.8

and 2,10. The'rotation of one of the gears is transmitted by shaft 212 to worm 214, 'and'worm 214. drives j gear 21 6 towhich control drum 21 is attached in the manner tobe describedbelow Movement of gear 216 also positions feedbackcam 213 to vary the area oforiiice 215 in conduit 2,17. 'Narying the-size-of orifice 215 varies the pressure supplied to bellows 219; Bellows'21 9 and 221 I are both supplied from, line 408, andconstitute a force feedback system to return flapper 1.62 to the null position thereby terminating the flow in iconduits 203 and 205;

programmed level, the pressure in chamber -46. will be reduced and the pressure in chamber 47 will be increased thereby moving piston 623 and'throttle valve 41 to increase the area of discharge passage 39 }The' increased area of Worm21'4 and gear 216 are of the irreversible type so I that the cessation of flow-to gear. motor 206 willaresult in a cessation of the rotation of shaft 212, and worm 214 and gear 216, and hence control drum 21,, will be a liquid hydrogen from the second stage of pump 11 flows through conduit 14 through cooling jacket 16 and thence through chamber 20' and through the core of reactor 28, and part of the; liquid hydrogen from .the first stage of I pump 11 flows through conduit 12 to shields 23-and 25 32 in a bootstrap manner, the driving fluid passing through the turbine causing a greater delivery of propel- 417 provides a continued flow of hydrogen through the portion of conduit 14 downstream of valve 15, and thence 'via cooling jacket 16, chamber. 20, chamber 27, through the core of reactor 28 tothrust chamber 19; This hydrogen flow continues for a predetermined period of time i and serves to remove the residual heat from reactor 28 and thrust chamber 19, and prepare the engine for an- 3 7 other cycle of operation. This flow of hydrogen is mainlant to chamber 17 from which the turbine po-wer fluid is extracted. The bootstrap operation of the pumping 1 system is controlledby turbine throttle valve 34 to regulatethe acceleration of the pumping systemandto establish and maintain the steady state operating condition as is determined by programmer 56. 1

The pressure in chamber 17 1s a measure of propellant flow, and this pressure is fed to turbine throttle valve 34 to be compared with the programmed signal from.

programmer 56, and the position of turbine throttle valve 34 is adjusted to'regulate the speed of pump tain the desired propellant flow.

A signal representing the actual temperature in chamber 17 is delivered to comparator 62 which in turn delivers a signal to drum control and actuator 64 via wires 73 to' adjust the position of controldrums 21'to main- 11 to maintain the programmed temperature Within chamber 17.

An emergency shut down is provided through-ion chamber 80 and amplifier- 82' which are calibrated to sense a.

sudden, large rate of change in reactor power level and activates solenoid valve 84 to deliver a scram signal to chamber 312 of drum control and actuator 64 to drive the control drums to the shutdown position.

If itis desired. to do so, a second ion chambersys- 'tem can be incorporated to sense a sudden, relatively mild rate of change of reactor power and deliver a controlled shut down signal to torque motor 166 of drum control d and actuator 64. t

Conduit 428 communicateswith chamber 27, and the pressurized hydrogen in chamber 27 is bled through conduit 428 andthrough check valve 430 to replenish the hydrogen in tank 4% which was used during start up. Solenoid valve 410 is closed either at a predetermined time after engine start up or at the initiation of engine shut down so that the supply in tank "400' can be preserved for further starts, and hydrogen is bled from chamber 27 via conduit 428 and conduit 404 for use as a supply pressure to operate the various control components during steady state engine operation. Also, the pressure in chamber 27 is delivered via conduit 432 to the top of tank as an additionalpressnrizing source for the hydrogen in tank 10, the tank pressurizationbcing regulated by orifice 434 in conduit 432.

In a normal shut down procedure, programmer 56 will deliver signals to turbine throttle valve 34 to close the throttle valve as a function of time to a point where the turbo pump stalls. From the turbo pump stall point on in time control 64 will be programmed to movecontrol drums 21 toward the full poison or shut downposition as a function of time. At the turbo pump'stall point, programmer 56'will deliver signals to simultaneously close solenoid valve'412 and open solenoid valve 415. The closing of valve 412 Will remove the hydrogen pressure signal from conduit 422 and results in the closing of shut off valves and 22 to prevent further hydrogen flow through either stage or pump 11. The'opentained by virtue of the pressure created within tank 10 resulting from boil-off of hydrogen Within tank 10. After a predetermined period of time, programmer 56 will del ver a signal 'to close valve 415 and hence close'valve 4 17 and end the afterheatremoval flow. Switch 106 will then be opened, and the engine will beprimedfor another cycle of operation.

Itis to be understood that the invention is not limited to the specific embodiment herein illustrated and described but may be used in other ways without departure from its spirit as defined by the following claims. I

l a propellant flow and control system for a rocket engine having a thrust chamber and a cooling jacket surrounding said thrust chamber, a source of propellant, means for pumping said-propellant including a two-stage pump, means for driving said pumping means, means for delivering a first part of said propellant from said second stage of said pumping means to said cooling'jacket, means communicating with said cooling jacketto receive said first part therefrom, means for delivering a second part of said propellant from said first stage of said pumping means to said receiving means to mix said first and second parts, means including heating means for delivering said mixture to said thrust chamber at an increased temperature, means for bleeding a part ofjsaicl mixture upstream of said heating means, means for bleeding a parrot said mixture from said thrust chamber, and means for mixing said bled parts and'delivering said mixture of bled parts tosaid pump driving means to power said pump driving 1 2. propellant flow and control system-as in claim l including means responsive to a condition of the mixture of bled parts for controlling the mixture of bled parts.

3. ia p ropellantiiow and control system as in claim 1 including means responsive to a condition of said' mixture of bled parts for controlling the amount of one of said .bled parts delivered to the mixture of bled parts, and

means responsive to thrust chamber pressure to regulate thelfiow of said first part of said ropellant to said cooling ac cet. i I v 1 4. propellant flow and control system as in claim 1 lDClllClli'lg means responsive to the temperature of the mixture of bled parts for controlling the mixture of bled parts, and control means responsive to a-condition of said mixture'downstream of said heating means for controlling the output of said heating means. 7

5. In a propellant flow and control system for a nuclear rocket engine having a thrust chamber and. a cooling jacket surrounding said thrust chamber, and a nuclear reactor upstream of said thrust chamber, a source of propellant, atwo-stage pump for pumping said propellant,

means for driving said pump, means for delivering part of the propellant from the first'stage of said pump to the second stage of said pump, means for delivering said part of the propellant from the second stage of said pump to means including conduit means for jacket through said reactor to said thrust, chamber, means heat removal valve 417. Valve 417-,is located in conduit 421 which extends from tank 10 toc'onduit 14 at a point 7 downstream of valve-15. Hence, the opening of valve for delivering the remaining propellantfrom said first stage pump to said conduit means to mixth'e propellant from the first stage and thesecond stage of said pump,

means forbleeding apart of said mixture upstream of said'reactor, means for bleeding a part of said propellant from said thrust chamber, means for mixing said bled parts and delivering said last-mentioned mixture to said driving means, means responsive to thetemperature of fying the power level of said reactor.

7. A propellant flow and control system as in claim including means for establishing a programmed opening of said throttle valve, means for establishing a programmed power level of said reactor, and means responsive-to the rate'of change of reactor power level for shutting down said reactor.

8. In the method of generating thrust in a rocket engine, the steps of pressurizing a first part of: a propellant, using said first part as a heat sink, pressuriz'ing a second part of the propellant to a level below the pressure level of the first part, mixing said first and second parts after the first part is used as a-heat sink, heating said mixture, expanding said mixture to produce thrust, bleeding a part of said mixture prior to heating, bleeding at part of said mixture after heating, mixing said bled parts, and utilizing said mixture of bled parts to pressurize said propellant.

9. The method of claim 8 including the further steps of sensing the temperature of said mixture of bled parts, and regulating the composition of said mixture of bled parts as a function of the temperature of said mixture of bled parts.

10. The method of claim 8 including the further steps of sensing the temperature of said mixture of bled parts, and controlling the amount of one of the bled parts delivered to said mixture of bled parts as a function of the temperature of said mixture of bled parts.

123 11. A propellant flow and control system as in claim 1 wherein said heating means is a nuclear reactor and including means responsive to the temperature of the mixture of the bleed parts for controlling the amount of one of said bleed parts delivered to the mixture of bleed parts, control means responsive to a condition of said mixture downstream of saidheating means for controlling the output of said heating means, and means responsive to the rate of change of the power level of said reactor operative to override said control means.

12. A propellant flow and control system as in claim -11 and including a programmer comprising means to dis- References Cited by the Examiner UNITED STATES PATENTS 2,676,456 Holzwarth u -356 3,028,729 4/62 Ledwith 60'35.6 3,033,774 5/62 Crever 204-1932 3,982,600 3/63 Williamson et a1. 6035.6 6/63 .Zinn 204l54.2 X

OTHER REFERENCES Dynamic Analysis of a Nuclear Rocket Engine System}? by Bernard R. Felix and Richard J. Bohl, ARS Journal, November 1959, pages 853-862.

SAMUEL LEVINE, Primary Examiner. V I SAMUEL FEINBERG, ABRAM BLUM, Examiners. 

1. IN A PROPELLANT FLOW AND CONTROL SYSTEM FOR A ROCKET ENGINE HAVING A THRUST CHAMBER AND A COOLING JACKET SURROUNDING SAID THRUST CHAMBER, A SOURCE OF PROPELLANT, MEANS FOR PUMPING SAID PROPELLANT INCLUDING A TWO-STAGE PUMP, MEANS FOR DRIVING SAID PUMPING MEANS, MEANS FOR DELIVERING A FIRST PART OF SAID PROPELLANT FROM SAID SECOND STAGE OF SAID PUMPING MEANS TO SAID COOLING JACKET, MEANS COMMUNICATING WITH SAID COOLING JACKET TO RECEIVE SAID FIRST PART THEREFROM, MEANS FOR DELIVERING A SECOND PART OF SAID PROPELLANT FROM SAID FIRST STAGE OF SAID PUMPING MEANS TO SAID RECEIVING MEANS TO MIX SAID FIRST AND SECOND PARTS, MEANS INCLUDING HEATING MEANS FOR DELIVERING SAID MIXTURE TO SAID THRUST CHAMBER AT AN INCREASED TEMPERATURE, ME ANS FOR BLEEDING A PART OF SAID MIXTURE UPSTREAM OF SAID HEATING MEANS, MEANS FOR BLEEDING A PART OF SAID MIXTURE FROM SAID THRUST CHAMBER, AND MEANS FOR MIXING SAID BLED PARTS AND DELIVERING SAID MIXTURE OF BLED PARTS TO SAID PUMP DRIVING MEANS TO POWER SAID PUMP DRIVING MEANS. 